Field
Embodiments disclosed herein generally relate to an optical device for use with processed substrates and methods of use. More specifically, embodiments generally relate to substrate integrity and alignment in thin film deposition.
Description of the Related Art
Substrates must be scanned for defects both before any patterning is done and after patterning to identify sites with defects that would lead to a defective device. As substrates become larger and pattern features become smaller, the problem of scanning becomes more difficult. Methods or strategies for improved scanning for defects thus become increasingly important in keeping the cost of inspection in line with the cost of patterning the wafers in the first place. In addition, rapid scanning of wafers and similar devices is important for extended production runs to avoid an accumulation of defective substrates upon entrance to the chamber or defective processed substrates due to processing issues.
With shrinking pixel size and fast refresh rate, display manufacturers face novel challenges. These challenges require the manufacturers to better control defects, film properties and thickness as the glass thickness itself shrinks. The thickness of the glass itself is related to glass breakage, which is consistently a key issue at customer fabrication facilities. A glass breakage brings the tool to a costly unscheduled “down”, or time period in which the tool is not active. A down due to glass breakage typically takes 18-24 hours to correct, making each down both expensive and non-productive. Further, aside from the lost productivity, the maintenance might require wet cleaning of the process chambers or transfer chambers to completely remove all microscopic debris which may remain in the chamber after the break.
Therefore, there is a need for improved devices and methods for substrate process control.